The present invention relates to the field of image processing. In particular, the present invention relates to still image processing in the compressed domain.
An increasing number of portable devices feature multimedia applications operating with audio and video. Such multimedia applications are increasingly attracting customers, which enthusiastically enjoy the use of the new multimedia features. Especially the market of portable phones or cellular phones illustrates the rapid acceptance of multimedia featured devices. Imaging phones, i.e. portable phones with image capturing capability, represent a class of portable phones, which are on the best way to represent the standard within a remarkable short period of time since introduction of this product class. The triumphant progress of imaging phones is attended by a comparable success of digital cameras.
Up to now, developments in the field of multimedia applications, especially image capturing applications, address recording/capturing quality, memory requirements, streaming capability (bit rate requirements), and replaying/displaying capability. Correspondingly, most research on multimedia applications has been focused on compression standards, synchronization issues, storage representations, and sensor designs. The field of techniques for processing digital images such as image manipulation including for instance editing (such as brightness adjustment, contrast enhancement, and sharpening), filtering, composing, and special effect implementation, has been paid scant attention.
The scant attention to the field of image processing is based on the complexity, i.e. computational complexity and data volume, required for image processing. Typically, portable devices handle digital images in compressed mode to meet the limitations of such portable devices, especially computational power and storage capacity, as well as requirements resulting from image handling including (wirelessly) receiving/transmitting images, streaming capability etc. Due to the complexity, image processing is a typical task implemented on current workstations and personal computers. These powerful processing devices allow for operating the brute-force algorithms, which include decompressing of the digital image in compressed mode, processing, i.e. manipulating the image in uncompressed domain, and compressing the manipulated image to obtain again finally the manipulated digital image in compressed mode. As aforementioned, modern compression techniques used for image compression are primarily optimized in view of the resulting size of the digital image in compressed mode accepting high computational complexity to obtain compression without degradation of the digital images or with degradation thereof in acceptable limits.
Nevertheless, the increasingly acceptance of multimedia applications will drive the request of the users/customers for image manipulation which are available on today's powerful home computer equipment.
Therefore, there is a need to provide efficient technologies and methodologies for efficient manipulation, editing, and processing of digital images on processing devices with limited processing capability including limited computational capability and limited storage capability. In particular, the technologies and methodologies presented apply user-desired effects, when manipulation, editing and, processing images, such as brightness adjustment, contrast enhancement, filtering, and sharpening on the images.